Jobs in London - Site Reliability Engineer • Central London

Company: Gizmo

Central London

Gizmo is an AI startup on a mission to make learning so easy that anyone can learn anything. We're building Duolingo for anything - a platform that uses gamification and social mechanics to make learning fun. With over 1 million monthly active users and $4M in annual recurring revenue, we’re already one of the fastest-growing startups in the UK. Backed by leading investors, we recently raised $22M in Series A funding to accelerate our vision of helping 1 billion people learn.Role OverviewReporting to the CTO, you will own capacity, performance and reliability for Gizmo’s full-stack platform as daily traffic climbs from hundreds of thousands to millions of users. You’ll write code across the stack, but your charter is classic SRE: defend SLOs, eliminate toil, and raise the ceiling on scale before it becomes a hard limit.Key Responsibilities Define SLIs/SLOs for latency, availability and error rate; codify error budgets and partner with product teams on trade-offs. Perform load-testing, capacity modelling and up-front scalability design for PostgreSQL, OpenSearch, Redis, Hasura and CF Workers; produce data-driven scaling plans. Extend metrics, structured logging and tracing; establish alert rules that page only on user-visible impact; build actionable runbooks. Join the on-call rotation, lead blameless post-mortems, drive remediation work to closure and track MTTR/MTBF improvements. Automate repetitive ops on Kubernetes and CI/CD; keep “toil” <50 % of your time by pushing fixes into code. Coach full-stack engineers on query optimisation, schema design and back-pressure techniques; document patterns and anti-patterns by creating an SRE playbook Requirements Hands-on scale experience: you have run relational stores at 100 k+ TPS or 1 M+ concurrent users (e.g., multi-tenant PostgreSQL, sharded MySQL). Strong backend fundamentals around concurrency, caching, indexing and distributed systems trade-offs. Proven track record of setting SLOs, building dashboards (Prometheus/Grafana, OpenTelemetry, etc.) and tuning alerts. Comfort with Kubernetes, IaC and cloud-native patterns; can debug from network to application layer. Self-starter with a maker mindset. We’re looking for ex-founders or individuals with start-up experience. Start-up bias for action: you prioritise high-leverage fixes, ship iteratively and own outcomes end-to-end. Collaborative and feedback-driven; you welcome post-mortem culture and continuous improvement. Driven by impact - you prioritise work that moves the needle! Nice-to-haves: experience with Hasura internals, Cloudflare Workers edge optimisation, or operating OpenSearch at scale.Benefits Highly competitive salary. You'll own a piece of what you're building - equity included. Hybrid working model with 4 days in our East London office, ideally located between Shoreditch High Street, Old Street, and Liverpool Street stations. The opportunity to become one of the earliest employees in one of the UK’s fastest-growing startups. Private health insurance